1. Field of the Invention
The present invention relates generally to coating compositions that contain surface active additives.
2. Background of the Invention
In many instances it is desirable to enhance the properties of a coating applied to a substrate. For example, additives are often employed in automotive and architectural coating compositions to improve the appearance and/or durability of the coating as well as to enhance the strength of the adhesive bond between the coating and the substrate and/or with subsequently applied coating layers. Such additives are typically employed in all types of coating compositions including liquid coating compositions, powder coating compositions and coating dispersions applied via electrocoating techniques.
Color-plus-clear coating systems involving the application of a colored or pigmented basecoat to a substrate followed by application of a transparent or clearcoat over the basecoat have become increasingly popular as original finishes for a number of consumer products including, for example, automotive vehicles. The color-plus-clear coating systems have outstanding appearance properties such as gloss and distinctness of image, due in large part to the clearcoat. Such color-plus-clear coating systems have become popular for use with automotive vehicles, aerospace applications, floor coverings such as ceramic tiles and wood flooring, packaging coatings and the like.
Other multi-layer composite coatings are commonplace in modern coating lines. For example, a typical automotive coating system can include the sequential application of an electrodeposition primer, a primer-surfacer, a color enhancing base coat, and a transparent top coat. In some instances, the electrodeposition primer is applied over a mill-applied weldable, thermosetting coating which has been applied to the coiled steel metal substrate from which the automobile body (or body parts, such as fenders, doors and hoods) has been formed. Also, adhesive coatings, for example, windshield adhesives, trim and molding adhesives and structural adhesives are sometimes applied to the cured top coats where necessary. Motor Vehicle Safety Standards (MVSS) require that these adhesives have complete adhesion to both the windshield and the coated substrate to which they are applied. Due to these multi-layer composite coating processes, it is necessary that the previously applied coating layer have excellent intercoat or interlayer adhesion to the subsequently applied coating layer(s) and/or adhesives.
There is recent interest in the automotive coatings market in eliminating the primer-surfacer step altogether, due to the resultant cost-savings. Top coats can be directly applied to the cured electrodeposition primer. In such modified coating processes, the electrodeposition primer is required to meet stringent durability and appearance specifications. Additionally, the cured electrodepositable primer must have excellent intercoat adhesion to the subsequently applied top coats (either monocoats or color coats of a color-plus-clear system).
During the assembly process, the applied color-plus-clear coating can include surface defects in the clear coat surface which requires repair. Some automobile manufacturers elect to remove the defect and recoat the repair area with the same clear coat composition. In this instance, the cured clear coat must have excellent intercoat adhesion to the subsequently applied clear coat. It is known, however, that some clear coats when cured have poor intercoat adhesion with the subsequently applied repair clear coat.
In view of the foregoing, there remains a need in the coating industry for coating compositions which have improved properties such as acid etch resistance and mar and scratch resistance while maintaining excellent intercoat or interlayer adhesion to subsequently applied coatings and/or adhesives.